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Posted to common-issues@hadoop.apache.org by "Kihwal Lee (JIRA)" <ji...@apache.org> on 2016/08/04 15:40:20 UTC

[jira] [Commented] (HADOOP-13442) Optimize UGI group lookups

    [ https://issues.apache.org/jira/browse/HADOOP-13442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15407961#comment-15407961 ] 

Kihwal Lee commented on HADOOP-13442:
-------------------------------------

+1 nice changes. The removal of synchronization looks safe after the changes to the static mapping.

> Optimize UGI group lookups
> --------------------------
>
>                 Key: HADOOP-13442
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13442
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>         Attachments: HADOOP-13442.patch
>
>
> {{UGI#getGroups}} and its usage is inefficient.  The list is unnecessarily converted to multiple collections.
> For _every_ invocation, the {{List<String>}} from the group provider is converted into a {{LinkedHashSet<String>}} (to de-dup), back to a {{String[]}}.  Then callers testing for group membership convert back to a {{List<String>}}.  This should be done once to reduce allocations.



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